Pump

ABSTRACT

Pump, in particular a servo steering pump for motor vehicles, having a flow control valve and a valve sleeve which has inflow openings to the flow control valve and a pressure connection to a hydraulic load.

The present invention relates to a pump, in particular to apower-steering pump for motor vehicles, having a flow-control valve anda valve sleeve which has inflow orifices leading to the flow-controlvalve and a pressure connection to a hydraulic load.

BACKGROUND

Pumps of this kind are generally known. In this context, the valvesleeves have a screw-fastened type pressure connection which is screwedinto a thread of the pump housing. However, numerous disadvantages areassociated with screw-in valve sleeves.

SUMMARY OF THE INVENTION

It is an object of the present invention to devise a pump which willovercome the disadvantages of the known valve sleeves.

The present invention provides a pump, in particular a power-steeringpump for motor vehicles, having a flow-control valve and a valve sleevewhich has inflow orifices leading to the flow-control valve and/or athrough-orifice for a throttling point and a pressure connection to ahydraulic load, the valve sleeve being designed as an insertion sleeveand being axially positioned in the pump housing by a securing device.

By designing the valve sleeve as an insertion sleeve, the benefit isderived that the insertion sleeve is able to be inserted into the pumphousing at a precise angular orientation. Moreover, there are noscrew-in forces acting on the thread which would have a deforming effecton the valve sleeve or the pump housing.

One preferred exemplary embodiment of the pump provides for the valvesleeve to have at least one transverse bore that is positioned relativeto an outflow bore in the pump housing. Thus, the design of theinsertion sleeve makes it possible to use just one single transversebore since the insertion sleeve is able to be positioned relative to thehousing during installation. Therefore, there may be no need for aplurality of transverse bores, as is the case when working with ascrew-in sleeve, thereby making it possible to provide an adequate flowcross section to the outflow bore.

Another preferred embodiment provides a pump where a pressure line isconfigured so as to be insertable into the pressure-connection side ofthe valve sleeve. It is also conceivable, however, that the pressureline may be screwed into the valve sleeve.

A pump is also preferred where the securing device is in the form of aflange that is attached to the pressure line. Here the advantage may bederived that the pressure line is also able to be installed at a preciseangular orientation since the flange predetermines the direction of thepressure line, thereby making it possible to observe predefinedpositions in the engine compartment of a motor vehicle.

A distinguishing feature of the pump according to the present inventionis that the flange is welded or soldered to the pressure line, orpressed in place or screwed into position on the same.

Another embodiment of the present invention provides a pump with adistinguishing feature that the flange has a plane mounting surface. Apump is also preferred where the flange has an angled mounting surface.Here the advantage may be derived that it is possible to vary thelocation specified for an attachment means for the flange on thehousing.

A pump is also preferred where the flange-mounting surface may besecured to the pump housing by at least one screw. Thus, once the screwis tightened, both the hydraulic line, as well as the valve insertionsleeve are fastened and secured in the axial direction of the valveinsertion sleeve.

Another pump according to the present invention has the distinguishingfeature that the securing device may be constituted of a flange that isfixed into place within the pump housing by interlocking deformation.This eliminates the need for an additional attachment means, such as ascrew, for example, thereby achieving a very space-saving, axialsecuring of the valve sleeve.

Another advantage of the insertion sleeve is that it may be insertedcentrically relative to the valve piston, particularly when theinsertion sleeve has a funnel-shaped valve seat for the valve piston,whereas a screw-in cartridge can lead to a widening of the valve bore inthe housing and to a misalignment between the valve piston and the valveseat due to a potential offset between the thread and the funnel-shapedvalve seat.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described below in greater detail withreference to the figures, which show:

FIG. 1 a cross section through a power-steering pump having an insertionsleeve according to the present invention and a corresponding flangecoupling at the pressure line;

FIG. 2 a plan view of the flange coupling;

FIG. 3 an angled flange coupling at a pump housing;

FIGS. 4 a and 4 b a valve sleeve having a flange that is fixed intoplace within the pump housing by interlocking deformation.

DETAILED DESCRIPTION

A power-steering pump 1 having a pump rotation group and a valveassembly is shown in cross section in FIG. 1. Of the rotation group,what is generally referred to as a control plate 3 is discernible withinpump housing 5, control plate 3 including kidney-shaped suction ports 7and kidney-shaped pressure ports 9 for a two-stroke vane pump. The rotorand the vane of the vane pump are not shown here. Illustrated in theupper portion of pump housing 5 is a valve assembly 11 which is capableof performing the combination function of a flow-control valve and of apilot-controlled pressure-limiting valve. A valve piston 15 isdisplaceably mounted in a valve bore 13 of pump housing 5. Valve piston15 rests by a sealing edge 17 against an approximately funnel-shapedseat of a valve sleeve 19. Valve sleeve 19, in turn, is insertablymounted within a widened portion 21 of valve bore 13. In addition, valvesleeve 19 has a through-orifice 23 in which a partially conical stem 25of valve piston 15, together with through-orifice 23, forms a variablethrottling point for the oil flow to the load. The load oil flow issupplied through pressure line 27 to the load, for example a hydraulicservo steering. Pressure line 27 is inserted in region 29 of valvesleeve 19 and is additionally provided with a seal 31. In addition,pressure line 27 has a flange 33 which, in this case, is attached by aweld joint to pressure line 27 and is secured by a screw 35 in housing5. An outflow bore 37 leads from the pressure region of the vane pumpinto the valve region where a corresponding inflow orifice 39 of valvesleeve 19 is configured to oppose outflow bore 37 in the housing. Due tothe fact that valve sleeve 19 may be positioned as an insertion sleeveoppositely to outflow bore 37 in housing 5, a clearly definedtransitional cross section is always obtained between outflow bore 37and valve sleeve 19. This is not possible using related-art screw-insleeves because, depending on the thread and the screw-down force, thescrew-in action results in a difference between the correspondingpositions of inflow orifices 39. The valve assembly in the upper portionof housing 5 also has a pressure-limiting pilot valve having a pilotvalve sleeve 41 in which a pilot valve cone 43 is sealingly supported ina valve seat 45 and is pressed by a spring 47 into the valve seat. Inresponse to the pretensioning force of spring 47 exceeding theadjustable maximum pressure, valve cone 43 opens by lifting off fromseat 45, and, together with valve piston 15, thereby provides apilot-controlled pressure-limiting valve. For as long as the maximumpressure is not exceeded, valve piston 15, which is pressed by a spring49 into sealing edge 17, functions as a flow-control valve piston andlimits the volumetric flow flowing out toward the load to a specificvalue. Flow-control valve and pressure-limiting valve functions of thiskind are sufficiently known from the related art and, therefore, do notrequire further clarification here.

Worth mentioning in this case is that the present invention makes itpossible for insertion sleeve 19 to be positioned relative to outflowbore 37, so that, as the case may be, it requires only one single infloworifice 39, while the related art requires using a plurality of infloworifices as outflow bores in order to realize the requisite hydraulicorifice cross sections. In addition, there are no screw-in forces actingon valve sleeve 19 or, therefore, on positioning bore 21. Under therelated art, these such screw-in forces can lead to deformations anddecentering. A further advantage is provided by pressure line 27 havingwelded-on flange 33 which may be mounted in the corresponding requisiteinstallation position for optional placement in the engine compartmentof a motor vehicle. A positionally correct installation is thus madepossible without the need for subjecting the pressure line to screw-inmovements. Both pressure line 27, as well as valve sleeve 19 are axiallyfixed into place at the pump housing by separate screw 35 between flange33 and pump housing 5.

A plan view of flange 33 of FIG. 1 is shown exemplarily in FIG. 2.Pressure line 27, which is shown in a sectional view, is attached byweld joint to flange 33. One single screw 35 is used to affix flange 33in the illustrated position to the pump housing. Thus, the position offlange 33 relative to the configuration of pressure line 27, as shown inFIG. 1, is fixed for the installation in the motor vehicle.

Alternatively, FIG. 3 shows a flange 51 having an angled mountingsurface 53. This makes it possible for a different surface of housing 5to be used as the connection surface for pressure line 27 for themounting attachment in the case that the intake plane of pressure line27 does not have any available space for a screw 55, and housing 5 doesnot have a corresponding thread.

Another variant of a valve insertion sleeve 60 is shown in FIGS. 4 a and4 b. In this case, valve insertion sleeve 60 has a flange 62 which, inFIG. 4 b, is fixed into place within housing 5 by four interlockingdeformation points 64. Here as well, it is possible to suitably positionthe inflow orifices of valve sleeve 60 and of housing 5, respectivelyoutflow bore 37 relative to each other. Also illustrated in FIG. 4 a areflow-control valve piston 15 and corresponding spring 49 which pressesvalve piston 15 against valve sleeve 60. Alternatively to an insertionpressure line, in this case, a screw-in pressure line may also bescrewed into an internal thread 66 of valve sleeve 60. However, thepressure line could be equally used as an insertion pressure line, inthe manner of pressure line 27 illustrated in FIG. 1.

LIST OF REFERENCE NUMERALS

-   1 power-steering pump-   3 control plate-   5 pump housing-   7 kidney-shaped suction ports-   9 kidney-shaped pressure ports-   11 valve assembly-   13 valve bore of pump housing 5-   15 valve piston-   17 sealing edge-   19 valve sleeve-   21 widened portion of valve bore 13-   23 through-orifice-   25 conical stem of valve piston 15-   27 pressure line-   29 region of valve sleeve 19 for pressure line 27-   31 seal-   33 flange-   35 screw-   37 outflow bore-   39 inflow orifice of valve sleeve 19-   41 pilot valve sleeve-   43 pilot valve cone-   45 valve seat-   47 spring-   49 spring-   51 flange-   53 angled mounting surface-   55 screw-   60 valve insertion sleeve-   62 flange-   64 interlocking deformation point-   66 internal thread of valve sleeve 60

1-9. (canceled)
 10. A pump comprising: a flow-control valve; and a valvesleeve having inflow orifices leading to the flow-control valve and/orto a through-orifice for a throttling point and a pressure connection toa hydraulic load, wherein the valve sleeve is an insertion sleeve and isaxially positioned in the pump housing by a securing device.
 11. Thepump as recited in claim 10 wherein the pump is a power steering pumpfor a motor vehicle.
 12. The pump as recited in claim 10 wherein thevalve sleeve has at least one inflow orifice positioned relative to anoutflow bore in the pump housing.
 13. The pump as recited in claim 10further comprising a pressure line configured to be coupled to thepressure connection side of the valve sleeve.
 14. The pump as recited inclaim 10 wherein the securing device is a flange attached to thepressure line.
 15. The pump as recited in claim 10 wherein the flange isrigidly affixed to the pressure line.
 16. The pump as recited in claim14 wherein the flange has a plane mounting surface.
 17. The pump asrecited in claim 14 wherein the flange has an angled mounting surface.18. The pump as recited in claim 16 wherein the mounting surface of theflange is secured to the pump housing by at least one screw.
 19. Thepump as recited in claim 10 wherein the securing device a flange fixedinto place within the pump housing by interlocking deformation.
 20. Thepump as recited in claim 15 wherein the flange is rigidly affixed to thepressure line by welding.
 21. The pump as recited in claim 15 whereinthe flange is rigidly affixed by soldering.
 22. The pump as recited inclaim 15 wherein the flange is rigidly affixed by being pressed inplace.
 23. The pump as recited in claim 15 wherein the flange is rigidlyaffixed by being screwed.